Treasure Island's Building One is seen in the foreground on Wednesday, March 30, 2011 on Treasure Island, San Francisco, Calif.

Photo: Lea Suzuki, The Chronicle

Treasure Island's Building One is seen in the foreground on...

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R. Scott of San Francisco reads a newspaper while sitting in the sun during an outing with his dog, Sam Sam, on Monday, March 28, 2011 in Treasure Island, San Francisco, Calif.R. Scott of San Francisco reads a newspaper while sitting in the sun during an outing with his dog, Sam Sam, on Monday, March 28, 2011 in Treasure Island, San Francisco, Calif.

Photo: Lea Suzuki, The Chronicle

R. Scott of San Francisco reads a newspaper while sitting in the...

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Mark Kroeger, Department of Public Works gardener, works in front of the Treasure Island Chapel on Monday, March 28, 2011 in Treasure Island, San Francisco, Calif.

Photo: Lea Suzuki, The Chronicle

Mark Kroeger, Department of Public Works gardener, works in front...

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Sculptures from the Golden Gate International Exposition flank the entrance to Treasure Island's Building One on Monday, March 28, 2011 in Treasure Island, San Francisco, Calif.

Photo: Lea Suzuki, The Chronicle

Sculptures from the Golden Gate International Exposition flank the...

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Passengers ride the 108 Treasure Island muni line on Wednesday, March 30, 2011 on Treasure Island, San Francisco, Calif.

R. Scott of San Francisco reads a newspaper as he pats his dog, Sam Sam, while sitting in the sun on Monday, March 28, 2011 in Treasure Island, San Francisco, Calif.R. Scott of San Francisco reads a newspaper as he pats his dog, Sam Sam, while sitting in the sun on Monday, March 28, 2011 in Treasure Island, San Francisco, Calif.

Photo: Lea Suzuki, The Chronicle

R. Scott of San Francisco reads a newspaper as he pats his dog, Sam...

No spot in the Bay Area has the obvious development potential of Treasure Island. None has such obvious pitfalls.

The 403-acre oval in the middle of the bay boasts a uniquely captivating setting, but its soil could turn to jelly in a major earthquake. Residents would live just 1.5 miles from downtown San Francisco, but the journey by car involves the perennially sluggish Bay Bridge.

None of this deters the boosters, who tout a project that in its own way would be as ambitious as the Golden Gate International Exposition, better known as the 1939 World's Fair, for which the island was created.

The sparsely developed former Navy base, which now houses 2,300 people, would house upward of 19,000 residents in 8,000 residential units lining the west and south shores of the island; an additional 230 acres would become open space ranging from ball fields to seasonal wetlands. Ferries would offer a 13-minute commute to downtown San Francisco. A 20-acre urban agricultural park might include greenhouses and orchards.

The plan addresses social goals, reserving 25 percent of the housing for low- and moderate-income residents. Several streets would be designed to favor pedestrians and bicyclists, not automobiles.

"We're trying to create a whole neighborhood, with a wide set of benefits for everyone who lives there," said Christopher Meany of Wilson Meany Sullivan, part of a development team that also includes Lennar Urban, Kenwood Investments and Stockbridge Real Estate Funds.

On Thursday, the City Planning Commission will be asked to give its final approval to both the environmental impact report for the project and the development itself, with a final hearing before the Board of Supervisors looming.

Transportation, quake safety

After five years of studies and negotiations, proponents still confront questions about two basic issues: transportation and seismic safety.

-- As a low-lying artificial island set between two major faults, geologists say that in its present state, Treasure Island's sandy soil could liquefy in a major earthquake and be threatened by rising sea levels.

-- Despite a plan that subsidizes ferry service and commuter buses, studies project that more than half of island residents will travel to and from work by automobile - a major strain on the Bay Bridge, which already is at capacity during commute hours.

Paying for improvements

A fresh question involves financing: the project was conceived as a redevelopment area, but Gov. Jerry Brown's move to scuttle the statewide system pushed developers and city officials this month to come up with a districtwide fee to pay for infrastructure improvements. This is a more costly approach, so the plan now includes 400 fewer units of affordable housing than were agreed to in 2006, a change sure to be debated in hearings ahead.

Other details have changed since the concept was introduced in 2005. The maximum number of housing units in the plan increased by 30 percent, even as several tower heights were lowered for aesthetic - and political - reasons. The ferry terminal was shifted to the south, leaving one-third of the residents outside the oft-touted 10-minute walk to ferry service.

Energy strategy scaled back

The current plan also trims some of the project's more aggressive environmental strategies.

In the original plan, for instance, construction of a central utility plant was described as a "key component" to reduce the island's energy use. The current documents say only that development "may include" a central plant.

If the $1.5 billion project is approved, developers anticipate two years of site work before construction of the first townhouses facing Yerba Buena Island. The initial phase also would include a small grocery within a 1938 airplane hangar, one of three buildings that remain from the World's Fair.

The project, which also includes roughly 200 housing units on Yerba Buena Island and a hilltop park, is expected to take at least 15 years to complete.

Stabilization: To protect the island from earthquakes and rising sea levels, engineers propose adopting a method often used to solidify landfills.

Transportation: Planners see mass transit as the best method to get commuters to their jobs in San Francisco and the East Bay. A15

From creation to development

1937 Treasure Island created with an eye toward future use as a regional airport.

2010 Navy agrees to transfer Treasure Island and its share of Yerba Buena Island to the city for $55 million, with additional payments if developers turn a profit. Revised plan with up to 8,000 units released, as is the draft environmental study.

2011 Developers and city officials seek final approvals. If this occurs, full development is expected to take at least 15 years.